When asked about happiness, we usually think of something extraordinary, an absolute delight, which seems to get rarer the older we get.

For kids, happiness has a magical quality. Their delight at winning a race or getting a new bike is unreserved (毫无掩饰的).

    In the teenage years the concept of happiness changes. Suddenly it's conditional on such things as excitement, love and popularity. I can still recall the excitement of being invited to dance with the most attractive boy at the school party.

    In adulthood the things that bring deep joy—love, marriage, birth—also bring responsibility and the risk of loss. For adults, happiness is complicated (复杂的).

    My definition of happiness is “the capacity for enjoyment”. The more we can enjoy what we have, the happier we are. It's easy to overlook the pleasure we get from the company of friends, the freedom to live where we please, and even good health.

    I experienced my little moments of pleasure yesterday. First I was overjoyed when I shut the last lunch-box and had the house to myself. Then I spent an uninterrupted morning writing, which I love. When the kids and my husband come home, I enjoyed their noise after the quiet of the day.

    Psychologists tell us that to be happy we need a mix of enjoyable leisure time and satisfying work. I don't think that my grandmother, who raised 14 children, had much of either. She did have a network of close friends and family, and maybe this what satisfied her.

    We, however, with so many choices and such pressure to succeed in every area, have turned happiness into one more thing we've got to have. We're so self-conscious about our “right” to it that it's making us miserable. So we chase it and equal it with wealth and success, without noticing that the people who have those things aren't necessarily happier.

    Happiness isn't about what happens to—it's about how we see what happens to us. It's the skillful way of finding a positive for every negative. It's not wishing for what we don't have , but enjoying what we do possess.

    Growing up in one of the poorest communities with most crimes in Los Angeles, US, being raised by a poorly-educated single mother and attending the worst-quality public school, not many people expected much of me, so I chose to expect something of myself.

    On my 12th birthday, I bought a poster of Harvard University to hang in my room. Being at Harvard became my dream: I saw myself attending class in Sanders Theater, studying in Widener Library and eating in Annenberg Hall. Driven by this dream, I kept studying hard. I'd begin my day by asking myself these two questions: “What do I want in my life?” and “Are the things I am doing today going to get me closer to that life?”

    Asking myself the questions gave me the courage to ask over 50 Harvard, students for advice on my application essays; it gave me the energy to study just one more hour on my SATs when others were asleep; and it gave me the determination to apply for just one more scholarship when already refused many times. Moreover, reminding myself of my goal each day made it easy to say no to the same choices my friends made, because they would never get me closer to my goal. I found that even being poor could not take away my power to decide what I choose to do with my life.

    Every day I could feel myself getting closer and closer to my goal as my writing got better, my SAT score increased, and my scholarship offers started coming in. On March 31st, 2011, an email arrived from Harvard. The first word was “Congratulations!”. Tears of joy filled my eyes.

    Who you are today is the result of the decisions you made yesterday, and who you will be tomorrow will be the result of the choices you make today. Who do you want to be tomorrow?

    Imagine, one day, getting out of bed in Beijing and being at your office in Shanghai in only a couple of hours, and then, after a full day of work, going back home to Beijing and having dinner there.

    Sounds unusual, doesn't it? But it's not that unrealistic, with the development of China's high-speed railway system. And that's not all. China has an even greater high-speed railway plan to connect the country with Southeast Asia, and eventually Eastern Europe. China is negotiating to extend its own high-speed railway network to up to 17 countries in 10 to 15 years, eventually reaching London and Singapore.

    China has proposed three such projects. The first would possibly connect Kunming with Singapore via Vietnam and Malaysia. Another could start in Urumqi and go through Kazakhstan and Uzbekistan, and possibly to Germany. The third would start in the northeast and go north through Russia and then into Western Europe. The new system would still follow China's high-speed railway standard. And the trains would be able to go 346 kilometers an hour, almost as fast as some airplanes. Of course, there are some technical challenges to overcome. There are so many issues that need to be settled, such as safety, rail gauge(轨距), maintenance of railway tracks. But the key issue is really money. China is already spending hundreds of billions of yuan on domestic railway expansion.

    China prefers that the other countries pay in natural resources rather than with capital investment. Resources from those countries could stream into China to sustain development. It'll be a win-win project. For other countries, the railway network will definitely create more opportunities for business, tourism and so on, not to mention the better communication among those countries.

    For China, such a project would not only connect it with the rest of Asia and bring some much-needed resources, but would also help develop China's far west. We foresee that in the coming decades, millions of people will migrate to the western regions, where the land is empty and resources unused. With high-speed trains, people will set up factories and business centers in the west once and for all. And they'll trade with Central Asian and Eastern European countries.

    You discover a shampoo that leaves your hair looking beautiful. But gradually, as you use it more, it's magical effects seem to disappear. "It's just your hair getting used to it, "your mom says. And so you put the shampoo away and look for your next wonder product.

    It sort of makes sense -why would something that left you looking nice at first suddenly start losing its effect after some time? Are there some other factors(因素)at play? Can your hair really get used to a certain shampoo?

    Marie Claire spoke to hair experts and it turns out that it's not true. Your hair cannot get so used to a product that it just stops working.

    So what is the deal? Cynthia Alvarez, a famous hair stylist, explained that there are a number of factors leading to your hair puzzle, but basically, it's not the shampoo. "A shampoo does not stop working because your hair get used to it, she said." If your shampoo stops giving you the results you want, the condition and needs of your hair have most likely changed, or the season may have changed -it's more humid(in $), the sun is stronger, or the air is drier. Your state of health may also be different from a recent illness.

    In other words, you need to give up blaming the shampoo. So what can you do to make your hair look beautiful for a little longer? Alvarez suggests changing your ways of hair care when factors, such as the weather, change. Experts also suggest keeping an eye on the amount of shampoo and conditioner(H%i )you're using because over conditioning can be bad for your hair.

    The spine (脊柱) stands at the center of your health, providing your body with structure and support. It also contains a major collection of nerves that deliver electric signals from the rest of the body to your brain. So it's important to take care of it.

    Staying in a good position is one of the most important things to keep your spine healthy. A proper position means standing or sitting while keeping your spins straight, except for its natural bending. Positions play a vital part even when you're asleep. Stomach sleeping is far from a good idea. Many people prefer sleeping on their side, which is in the interests of their spine. Sleeping on your back has lots of benefits yet can cause lower back pain and put some pressure on your spine.

    Staying still for too long — even if your position is good — can be hard on your back. Especially if you work at a task most of the day, it's important to get up and stretch (伸展) periodically. Strength exercises with light weights like push-ups can also help by strengthening the muscles. However, don't overdo the exercise, as repeated movements can hurt the muscles around the spine, as trying to lift heavy weights with poor technique.

    Vitamins also affect the health of your spine. In particular, vitamin B and omega-3 fatty acids help keep nerves healthy. Another important part is vitamin D, which is required for strong bones. Vitamin D can come from some foods, but it's also absorbed from sunlight, so it may help to do some exercises outside. At last, many of the actions necessary to keep a spine healthy are similar to those used to protect your health in other ways. So protect your back, and the rest of the body will benefit.

    Janus, the Roman god, has two faces looking in opposite directions. So does artificial intelligence (AI). On one side are the positive changes, enabling people to achieve more, far more quickly, by using technology to improve their existing skills. Look the other way, though, and there are plenty of potential pitfalls.

    Like Janus, technological change may also cause disruption(混乱), but AI is likely to have a bigger impact than anything since the appearance of computers, and its consequences could be far more disruptive.

    In the years ahead, AI will raise three big questions for bosses and governments. One is the effect on jobs. Although CEOs publicly praise the broad benefits AI will bring, their main interest lies in cutting costs. One European bank asked Infosys to find a way of reducing the staff in its operations department from 50,000 to 500. The McKinsey Global Institute estimates that by 2030 up to 375m people, or 14% of the global workforce, could have their jobs replaced by AI.

    A second important question is how to protect privacy as AI spreads. The internet has already made it possible to track people's digital behavior in minute detail. AI will offer even better tools for businesses to monitor consumers and employees, both online and in the physical world. Consumers are sometimes happy to go along with this if it results in personalised service or promotions. But AI is bound to bring invasion of privacy that is seen as unacceptable. For example, law-enforcement officials around the world will use AI to spot criminals, but may also monitor ordinary citizens.

    The third question is about the effect of AI on competition in business. A technology company that achieves a major breakthrough in artificial intelligence could race ahead of rivals, put others out of business and lessen competition. This is unlikely to happen in the near future, but if it did it would be of great concern.

    It is too early to tell whether the positive changes brought by AI will outweigh the risk. But it will put an end to traditional ways of doing things and start a new era for business and for the world at large.